Thanks for testing this. I have raised a case with nintex support and they released a hotfix which solved the workflow being suspended however another issue came up where I couldn't open the workflow designer.. so they are looking into this

From looking at the error message, my guess is you have some web service request actions in your workflow "Call web service" or "Http Web request". And it could the web service url you are calling does not exist or invalid.

It would help us help you if you can provide some info on where in the workflow its failing?

As Nintex workflow for office 365 does not have the graphical view of the workflow history, I usually use "log in history" at before and after critical points where it may fail. This way makes it easy to identity which workflow action has failed.

Apologies for the late reply. I have tested setting the workflow status to "Request Pending" and it worked ok.

In a separate note, I found that this status column doesn't always update reliably. I had one scenario where the first workflow instance successfully set the status to "started" . When you kick off another instance on it that status column will remain "started" even if it should have changed to "in progress". It seems to only retain the status of the first workflow instance.

Thanks for testing this. I have raised a case with nintex support and they released a hotfix which solved the workflow being suspended however another issue came up where I couldn't open the workflow designer.. so they are looking into this